Couples attempting to conceive have approximately a 1 in 7 chance of being infertile at one year. Unfortunately, no validated markers exist to predict future infertility for couples initiating or delaying the process of reproduction. Despite limited supporting evidence, markers of ovarian aging are being measured at doctor's offices and in commercial home kits as a method of assessing women's fertility. Our long term goal is to examine the ability of markers of ovarian aging to predict infertility in the general population. The objective of this small, exploratory study is to determine the extent to which markers of ovarian aging associate with fecundability (probability of conception per cycle) in a reproductive age population of unknown fertility potential. Findings from this study will be used to select the number, timing, and choice of markers for predictive testing in a future, larger cohort. The proposed study will enroll 100 women from the community, who desire to conceive, and obtain baseline measures of ovarian aging: early follicular phase serum follicle stimulating hormone, inhibin B, and anti-mullerian hormone. Participants will be actively followed throughout their attempts to conceive over the following six months. During that time, women will collect urine during the early follicular phase of each cycle for FSH measurement, conduct up to two home pregnancy tests per cycle for standardized pregnancy determination, and complete a daily diary for up to three menstrual cycles for collection of detailed exposure data. These methods will allow us to address our primary research aims: (1) generate preliminary estimates of the association between fecundability and markers of ovarian aging and (2) determine the cycle-to-cycle variation in an individual's markers of ovarian aging. The primary tools for the proposed study including a web-based diary system, computer-assisted interviews, data management and quality control systems, and experienced staff are in place, assuring feasibility. A simple, validated measure of reproductive potential would be of significant benefit to women, who are considering initiating or delaying childbearing. Given that unproven home urinary kits are already being marketed, a prospective study to determine their ability to predict fecundability and fertility in the general population is essential. PUBLIC HEALTH RELEVANCE: Couples attempting to conceive have approximately a 1 in 7 chance of being infertile at one year, resulting in significant distress and anxiety. A simple, validated measure of reproductive potential would be of major benefit to women, who are considering initiating or delaying childbearing. Given that unproven home urinary "fertility test" kits are already being marketed, a prospective study to determine their ability to predict fecundability and fertility in the general population is imperative.